Scanning device



Aug. 22, 1967 1 s. SLIKER 3,337,683

SCANNING DEVICE Original Filed May 23, 1963 2 Sheets-Sheet l s 9o 36 383 a 40 54 84 N [l/111111111171111 lll/0l! i.m- N Y MWI/111110111111112 r2s 2O 24 25 82 S FIGA INVENTOR LAWRENCE sisLlHER BY FIG 3 o ATTORN EWAug- 22', 1967 L. s. SLIKER 3,337,683

SOANNING DEVICE Original Filed May 23, 1963 ,2 Sheetsheet 78 eo 74 7o 7I6 83 o 27e 2o INVENTOR. LAWRENCE S. SLIHER. 300

ATTORNETl United States Patent O 3,337,683 SCANNING DEVICE Lawrence S.Sliker, Rochester, N.Y., assignor, by mesne assignments, toInternational Scanning Devices Limited, Chippewa, Ontario, Canada, acorporation of Canada Continuation of application Ser. No. 282,739, May23,

1963. This application Aug. 2, 1966, Ser. No. 570,139

16 Claims. (Cl. 178-5.4)

ABSTRACT F IHE DISCLOSURE For use in television or the like, a atscanning unit utilizing crossed conductors on opposite sides of anelectroluminescent layer in a scanning section, 'and a viewing sectionincluding a pair of conductive layers sandwiching therebetween aphotoconductive layer, an opaque layer, and a light transducer layerwith means for providing a high-frequency potential between theconductive layers, modulated in :accordance With an information signal;an improved means for sequentially energizing the conductors of thescanning array by the provision of aligned gaps and magnetic controlmeans extending along the line of gaps to drive a spark from gap to gapand thus effect sequential energization. In addition, minute conductiveelements extending through the opaque layer in the viewing section, anda color reproducing arrangement wherein the uppermost conductive layeris subdivided into strips corresponding to separate colors, with eachstrip associated with a color being electrically interconnected witheach of the other strips of the same color association, the sets ofinterconnected strips being connected with the first conductive filmthrough high frequency potential producing means modulated in accordancewith the separate colors.

Detailed description This is a continuation of application Ser. No.282,739, iiled May 23, 1963.

This invention relates to an electroluminescent display orphotosensitive unit for television, radar and the like.

The display unit commonly used for television and radar is based on theconventional cathode ray tube wherein an electron beam from a hotcathode is caused to scan a fluorescent screen in order to reproduceinformation transmitted from a distant source. Such tubes are bulky inthat considerable `depth is required to accommodate a beam of sutlicientlength for deflection purposes necessary to scanning. In addition, suchtubes, being evacuated, must be so shaped as to withstand atmosphericpressure particularly over its screen supporting face, necessitating anarched and generally circular configuration. Since the scanningoperation is effected over .an area of rectangular shape, the circularshape cannot readily accommodate all of the information transmitted fromsource, unless the circular size of the screen is made oversize tocircumscribe the rectangular area. Such tubes require a high potentialbetween the cathode and screen, and sweep circuits acting throughdeection coils or plates to effect scanning.

The present invention lis directed to a display unit which may 'berectangular, fiat or curved as desired :and of uniform and extremelyshallow depth, and in which use of a hot cathode and beam in anevacuated envelope, as Well as beam deflection means -are completelyeliminated. More particularly the present invention is directed to a atplate layer like display unit having a built in scanning section, and aluminescent display unit actuated by the scanning section, the latterhaving intensity modulation control means. While the invention isparticularly adapted to providing a rectangular display,it may 'bemodified for circular display.

3,337,683 Patented Aug. 22, 1967 The above and novel features of theinvention will appear more fully hereinafter from the following detaileddescription when taken in conjunction with the accompanying drawings.Itis expressly understood that the drawings are employed for purposes ofillustration only and are not designed as a definition of the limits ofthe invention, reference being had for this purpose to the appendedclaims.

In the drawings, cate like parts:

FIGURE 1 is a fragmentary diagrammatic section view through theelectroluminescent display unit;

FIGURE 2 is a sectional View taken substantially on the line 2 2 ofFIGURE l illustrating the scanning portion of the unit;

FIGURE 3 is a fragmentary diagrammatic view of a modification of theouter layers of the device;

FIGURE 4 is a fragmentary sectional view similar to FIGURE .2, showingmodication of the scanning unit to produce interlaced pictures; and

FIGURE 5 is a plan diagrammatic view of a modified form wherein scanningand information control is combined.

Referring to the drawings, there is shown `a rectangular envelope formedof spaced glass plates 20` and 22, which may be peripherally sealedaround the edges in any suitable manner as by fusing the glass platestogether or by use of an epoxy as at 19. Disposed within the envelope isa scanning section comprising two layers 24 and 26 of parallelconductive lines, or conductors 25 and 27 respectively, arrangedperpendicularly with respect to each other, and an yintervening layer ofelectroluminescent material 28. The layer of conductive lines 25 issupported upon the inside face of the glass plate 20, while the layer ofconductive lines 27, is supported on the under face of a gl-ass plate30. The conductive material of which the lines 27 are composed, is oftransparent material such as tin oxide, SnOZ.

Above the scanning section is a light intensity control sectionconstituting an famplier or modulating screen. For this purpose, theupper face of the glass plate 30 is provided with a coating 32 oftransparent conductive material, which may likewise be of tin oxide, andthe inside face of the envelope plate 22 is provided with a coating oftransparent conductive lmaterial 34, which may also be of tin oxide.Disposed between the conductive layers 32 and 34, is a layer ofphotoconductive material 36, which may be of cadium sulphide, CdS, orthe like, and a layer of electroluminescent material 38, which may be ofzinc sulphide, ZnS, the layers 36 and 38 lbeing separated by a layer 40`made up of a multiplicity of minute conductive elements each surroundedby a suitable insulating material, such layer being opaque.

Referring again to the scanning section, each of the layers of parallelconductors are alike, with the exception that the conductors 25 of thelower layer 24 need not be of transparent material.

Referring to FIGURE 2 wherein the superimposed layers 24 and'26,separated by electroluminescent material 28, are illustrated, there areshown the conductors 25, of the under layer. At one end, and beyond thescreen area, each conductor 25 is provided with a discharge gap 54, andthe terminal ends 56 of all the conductors, are connected together as at60, and to a common lead 62 extending through the envelope.

In a similar manner, all of the transparent conductors 27 of the upperlayers are provided with a discharge gap 70. The terminal ends 72 of allof the conductors 27 are connected to a common return 76, which is inturn provided with a connecting lead 7f8 extending through the envelope.Adjacent to one of the end discharge gaps 54, is a triggering dischargegap 58, connected to the lead 60, and to lead 64 extending lthrough theenvelope. In

wherein like reference characters indi- 3 the same manner, a triggeringdischarge gap 74 is provided adjacent to one of the end discharge gaps70, and is connected to the common return 76, and a lead 80 extendingthrough the envelope.

Magnetic fields, which may be produced :by any suitable means, areestablished along the line of the gaps 70. Each magnetic eld, which isperpendicular to the plane of the conductors 25 and 27, may be ofuniform intensity along the entire line of each row of gaps, and maycom-prise a pair of pole pieces. The magnetic field along gaps 54 maycomprise pole pieces 82 and 84 disposed along the underside of the plateand the upper side of plate 22, in alignment with the gaps 54, asindicated `in FIGURE 1. The pole pieces may be connected by a yoke 86,extending around the peripheral edge adjacent the gaps 54. A secondmagnetic field is established along the line of gaps '70, in a similarfashion -by pole pieces 88 and 90. The pole pieces may be bars ofpermanently magnetized material, or may be of iron, magnetized by theyoke, which may be a permanent magnet, or magnetized by a magnetizingcoil. The fields may also be produced 'by other suitable means such aselongated coils energized by direct current, and disposed below (andabove if desired) and in alignment with the series of gaps 70. Suchcoils may be disposed within the envelope adjacent the gaps and may havefield concentrating cores. The magnetic field of the vertical scanning,between pole pieces 82 and 84, may be caused to pulse to control themovement of the discharge from one gap to the next, in a precise manner.Thus when a magnetizing coil is used, to produce the field, the directcurrent potential applied to the coil is momentarily increased, orpulsed, to cause the discharge to move to the next gap.

The envelope will be filled with an inert gas under suitable pressure topermit an ionized glow discharge across the gaps 54 and 70 andtriggering gaps 58 and 74, upon application of predetermined potentialsthereacross.

Assuming lead 62 is connected to the positive terminal of a source ofdirect current potential, and lead 78 is connected to the negativeterminal, and the potential is just under the value requisite to breakdown any one of the gaps 54, and any one of the gaps 70, no currentflows, between any of the conductors 25, and conductors 27 through theconductive electroluminescent layer 28. Should there be a simultaneousdischarge or breakdown across gap 70A and gap 54A, for example, acircuit is completed, see FIGURE 2, from conductor A to conductor 27A atL across the electroluminescent material 28, and luminescense wouldoccur at L.

With such potential applied to the terminals 62 and 78, triggeringpotentials are simultaneously applied to the leads 64 and 80. A negativetriggering potential is momentarily applied to the lead 64, sufficientto discharge at the gap at 58, thereby ionizing the gas in the immediatevicinity thereof. At the same time a positive triggering potential isapplied to lead `80, sufiicient to discharge and ionize the gas in theregion of gap 74.

Under the influence of the magnetic fields associated with therespective gaps 58 and 54, and gaps 74 and 70, the discharge across thetriggering Vgaps 58 and 74 are caused to arc of warp toward theimmediately adjacent gaps 54 and 70 respectively, ionizing the gas inthe region thereof whereupon discharge across such gaps takes place,causing luminescence t0 occur initially at I due to the circuitcompleted across the electroluminescent material at the cross over pointof the conductors 25 and 27 at I. The magnetic field tends to wa-rp lthedischarge in the gaps 54 and 70 away from the triggering gaps 58 and 74,and into the region of the immediately adjacent or second `gap 70. Byproviding a relatively strong magnetic field between poles 90 and 88 thetriggering discharge may 'be transferred to the gaps 70, and thedischarge caused to advance from gap to gap from left to right, whiledischarge at the initial gap 54 continues, thus causing the luminescentspot I to move along conductor 25 from left to right. The magnetic fieldstrength between pole pieces 84 and 82 is such as to cause the dischargetriggered in the first gap 54 to also travel from gap to gap from top tobottom, but at a rate such that the discharge travel from one gap 54 tothe next gap occurs in the time interval required for the dischargeacross gaps 70 to travel the entire sequence. Thus the luminescent spotI travels from left to `right along the initial conductor 25, before thedischarge across the initial gap 54 ionizes the gas sufficiently in thevicinity of the adjacent gap 54 to effect discharge. When the dischargeacross the sequence of gaps 70 reaches the right end gap, the arcingeffect due to the magnetic field terminates the discharge. A secondtriggering impulse is then impressed on lead which initiates a secondtravelling discharge across gaps 70, and since the discharge across theinitial gap 54 has moved to the next gap 54, the luminescent spottravels from left to right along the Second conductor 25. Similarly whenthe luminescent `spot has travelled the length of the second conductor25, the discharge in the right hand end gap 70 is extinguished, and athird triggering potential is applied at gap 74 to initiate a thirdsequential discharge across gaps 70, after the discharge at the secondgap 54 has moved on to the third gap 54. Thus the spot of luminescenceis caused to scan along the successive lines 25, one at a time from topto bottom. When the discharge across gaps 54 reaches the lower end gap54, it is extinguished and a triggering impulse is then applied to gap58 togther with a succession of triggering impulses applied to gap 74 toprovide a second complete scanning.

While only a small number of horizontal and vertical conductors 25 and27 have been shown in FIGURE 2, for illustrative purposes, in scanningfor television with no inter-lacing, 263 horizontal lines would beemployed, while there would be approximately 350 vertical lines. Thusfor 30 pictures per second, gap 58 would be triggered `60 times persecond while gap 74 would be triggered 15,750 times per second.

The conductive plates 32 and 34 are connected to a source of highfrequency potential, in the order of 18 megacycles or greater, theamplitude of which is varied in accordance with the modulation of theinformationcontaining signal, which signal may also contain thetriggering pulses applied periodically to leads 64 and 80. Theluminescence of screen 28 at the scanning point renders thephotoconductive plate conductive immediately adjacent the scanningpoint, and a condutive path between plates 32 and 34 is thereby effectedthrough the conductive plate, one of the minute isolated conductiveelements 39 in the opaque screen 40, and the electroluminescent layer38. Since the high frequency potential applied to plates 32 and 34 ismodulated by the signal strength, the degree of luminescence effected inlayer 38 varies in accordance with the modulated potential applied toplates 32 and 34. It will be understood that the brilliance of thescanning trace in layer 28 will be constant, and that its effect on theconductance of the photoconductive plate will be uniform, and thus thedegree of luminescence in plate 38 will vary with the signal modulationof the high frequency potential applied to the plates 32 and 34. Sincethe conductive plate 34 is of a transparent substance such as tin oxide,the modulaetd luminescence visually reproduces the picture or otherinformation carried by the modulated high frequency potential applied toplates 32 and 34, the luminescence of the trace in plate 28 being hiddenby the opaque plate 40. The minute conductive elements 39 of plate 40serve to concentrate the conductive path of current flow between theplates 32 and 34, it being understood that such path continuously moveswith the scanning trace.

By subsituting for the conductive plate 34, a plate having a series ofseparate parallel conductors, two for each scanning line conductor 25,to provide two sets of intermes-hing conductors, and by subdividing theadjacent electroluminescent layer 38 with a number of stripscorresponding to the number of parallel conductors of plate 34, witheach strip in registry with a corresponding pairallel conductor of plate34, and with the strips alternating in color luminescence, so thatalternate strips are luminescent in one color, and the remaining stripsluminescent of a second color of two colors capable of producing fullcolor pictures, a full color picture can be produced by applyingseparate high frequeny information modulated voltages between each setof the conductois and the conductive plate 32.

As illustrated in FIGURE 3 the conductive plate 34 is subdivided by aseries of transparent conductive lines, 100 connected together as at101, and a second set of conductive lines 102 connected together as at103. The electroluminescent layer 380 is subdivided into sections 104 inregistry with conductive lines 100, and alternate sections 106 inregistry with conductive lines 102. The sections 104 luminesce in onecolor, while the sections 106 luminesce in another color, the two colorsbeing chosen to take yadvantage of the Land system of producing fullcolor pictures from two colors. Each of adjacent conductive lines 100and 102 will be in registry with a scanning conductive line 25. The highfrequency potential modulated in accordance with one color is connectedto the lead 101 and plate 32, while the second high frequency potentialmodulated in accordance with the second color is connected to the .lead103 and plate 32. For employing conductive material for the lines 100which is semitransparent and transmits one band of color, and conductivematerial for the lines 102 which is sernitransparent and transmits adifferent band of color, of a two color system, the luminescent screen38 need not be divided into sections, but may be continuous iandgenerate white light. Thus 'by energizing the lines 100 and 102 by thecolor con- Itrol signals, a color picture is produced.

The apparatus may be modified so as to operate for television camera useby the substitution of a photoconductive layer for theelectroluminescent layer 38 shown in FIGURE 1. Thus as a picture orother information is projected upon the photoconductive layer thussubstituted for the electrol'uminescent layer 38, through thetransparent conductive layer 34, the conductance between the conductivelayers 34 and 32 will vary in accordance with the light intensity at anypoint in plate 38 coextensive with the photoconductivity in the plate 36produced by the scanning luminescent spot in electroluminescent layer28.

By further modification the apparatus may operate as a television cameraresponsive to color. For this purpose the conductive plate 34 issubdivided in the manner illustrated 'in FIGURE 3, employing conductivesemi-transparent light filtering materials, the conductors 100 being,for example, capable of transmitting one color, while the conductors 102transmit a second color, or a two color Land system. With layer 38photoconductive and segmented with a separate segment unde-r eachconductor, with segments insulated from one another, and with each pairof con'ductors 100 and 102 in registry with a trace conductor 25, itwill be seen that during any trace the conductance of thephotoconductive layer will respond to the color intensity fallingthereon through the light filter conductors 100 and 102. Thus theconductance between plate 32` and conductive lines 100 and lead 101, andthe conductance between plate 32 and conductive lines 102 and lead 103will be made to vary in accordance with the intensity of the two colorsat any point corresponding to the scanning trace, the conductive pathbetween conductors 100 and plate 32, and conductors 102 and plate 32,being concentrated by the minute conductive elements 39 in the opaqueplate 40. Thus the varying conductances between plate 32, and leads 101on the one hand and lead 103 on the other hand, may be employed `tomodulate the carrier frequencies for transmission of the colorinformation received by the camera as scanned.

It will be understood that any space between the adjacent conductorsIand 102 will be opaque to prevent light entering the photoconductivelayer except through the filters. In practice the photoconductive layer,segmented` as above set forth, may have each of its segments subdividedto provide a checkerboard effect, with each individual subdivisionsinsulated from one another. In such case, the opaque layer 40 may beeliminated.

While a two color system has been referred to for illustration, it willof course appear that by subdividing the conductive film 34 in groups ofthree, and by subdividing the layer 38 accordin-gly, a three colorsystem, both for producing pictures, or providing a camera receptive tothree colors may `be had.

In FIGURE 4, there is shown a schematic view of an upper fragment of thescanning section adapted for interlacing wherein the verticalconductors, and their respective gaps 70 and triggering gap 74 andmagnetic field, are the same as in FIGURES 1 and. 2. The horizontalconductors with their gaps 154, adapted to be periodically triggered bythe gap 158, alternate with conductors 124 having gaps 153 tri-ggered bya gap 157. It will be seen that the direction 4of the magnetic fluxacross the gaps 158 and 154 will `be opposite to the direction of theflux in gaps 157 and 153 since the sequential discharge in gaps 154 bygap 158 and the sequential discharge across gaps 153, triggered by thegap 157, will both travel downwardly, and since current flow across gap154 will be from right to left, whereas current flow in gap 153 is fromleft to right, the `gaps 153 having been disposed along the oppositeedge, to facilitate construction. In operation, the action diifers fromthat heretofore set forth, in that tors 124. Thus if a complete scanningof the Ione section is. effected in 1/60 of a second followed `by acomplete scanning of the other section 1/60 of a second, two interlacedpictures will be produced each 1/30 `'of a second. For standardbroadcast, any number of conductive lines 27 may be employed, such as700, Whereas the total number of conductive lines 125 and 124 may be525..

any one of gaps 254 during discharge. Similarly `the opposite or righthand ends of the conductors 224 are offset around the area of gaps 254and each connected to a common return 263 through a resistance 262 ofthe same value as the resistance of gaps 253 during discharge.

The vertical conductors may be arranged in two sets of conductors 227and 226, for color picture pnoduction, with gaps 270 and 269 at theirrespective ends, triggered Aby gaps 274 and 273 respectively. Theconductors 227, at their opposite ends are oifset to clear the gaps 269,and are each connected through a resistor 280 to a common return 281,and the conductors 226, at their ends opposite from their gaps 269 areoffset to clear gaps 270, and are in turn each connected through aresistor 283 t-o a common return 232. The resistors 280 and 283 have thesame value as the resistance of their respective gaps during discharge.

By applying direct current potentials between terminals 261 and 162 andterminal 281 and 276 of equal values and providing means for maintainngthe potentials at the terminals 281 and 162, at a predetermined valuewith reference to ground, `with the potential at terminals 261 and 276also at a predetermined potential with reference to ground, it will beseenn that as the discharge travels the sequence of gaps 270, thecorresponding conductors 227 will be sequentially brought to a midpotential half way between the potential applied at 281 and 276. Also asdischar-ge across any one of gaps 254 takes place the corre spondingconductor 225 will be `brought to the same mid potential. Thus thevoltage impressed upon the electroluminescent material between theconductors 225 and 227 at any point where a discharge energizedconductor 225 `crosses a discharge energized conductor 227, both ofwhich conductors are a mid potential due to simultaneous dis- `charge intheir respective gaps 254 and 270, will be zero. Thus scanning iseffected without creating any electroluminescence in the layer 28. Byimpressing upon terminals 276 and 162 a high frequency signal, amplitudemodulated in accordance with picture information, the electroluminescentlmaterial may be caused to luminesce, with brightness in accordance withthe modulated amplitude of the high frequency potential impressed acrossthe teryminals 276 and 162. Such modulated signal frequency may beimpressed upon the terminals 276 and 162 by inductively coupling themodulated signal frequency as at 290 with an inductance 292 `connectedthrough capacitances 294 and 296 to the terminals 276 and 162. Thus theluminescent material is scanned as a dark spot by the dischargesequences occurring in gaps 270 and gaps 254, and luminescence invarying degree will only be effected at the otherwise dark spot scannedby response of the luminescent material to the amplitude of the signalfrequency.

The above description, for illustrative purposes, has been made toscanning as between conductive lines 227 and 225 as though conductivelines 226 and 224 were non-existent, and such Aoperation will produce ablack and white picture, viewable from either side, if the conductivelines 227 and 225 are both of transparent conductive lines 227 and 225are both of transparent conductive material, such as tin oxide. Howeverin practice, viewing would be from one side only such as through thelines 227, since from the other side a reflective, in effect, reverseimage would be produced. In order t provide picture interlacing,scanning is effected first by employing a combination of conductivelines 224, the incoming signal frequency being impressed u-pon conductor265, through the additional capacitance 297. Thus interlacing iseffected, as will be understood from a consideration of the descriptionin conjunction with FIGURE 4. It will be understood that the samepotential is applied across leads 265 and 263, as was applied acrossleads 162 and 261 to ground, so that zero voltage scanning results fromeither set of conductors 225 and 224, in reference to conductors 227.

Color picture utilizing, for example, the two color Land system referredto, may be effected by utilizing two sets of vertical conductors, oneset being conductors 227, and the other set being conductors 226. Theconductors 227 will be adapted to transmit light of one color of thesystem, while the conductors 226 will transmit the other color. The samedischarge potential as is applied across leads 276 and 281 will beapplied across leads 275 and 282 having the same reference to ground, soas to produce zero potential scanning. A carrier frequency, modulated byone color band of information, will be impressed upon inductance 292, byinductance 290, to produce luminescence as between conductors 227 and225 and 224. A second carrier frequency, modulated by the other colorband of information will be impressed upon inductance 302, by inductance300, and will produce luminescence as between conductors 226, and 225and 224, the inductance 302 be- 8 ing suitably coupled to conductors265, 162, and 275, through suitable capacitors 304, 306 and 308respectively.

The same scanning section illustrated in FIGURE 5 becomes a camera uponsubstituting a photoconductive layer, for the electroluminescent layer28. The photoconductive material may be cadmium sulphide. For black andwhite, camera operation, conductors 227 will be transparent. For color,using the two color system referred to, the conductors 227 and theconductors 226 will be of light filtering material. The conductors 227will transmit to the photoconductive material 28 one color band, whilethe conductor 226 will transmit to the photoconductive layer the secondband. Thus as an im-age is projected upon the layers of conductors 227and 226, during scanning, the conductivity of the layer 28 will vary dueto the light intensity impressed thereon. The variation in conductancein the photoconductive layer during such scanning may be readily used tomodulate a carrier frequency. Instead of the conductors 225 and 224, andthe conductors 227 and 226 being brought to the same potential by gapdischarge, so that zero potential scanning is effected, a resistor isinserted in each of leads 316 and 318, so that on discharge at a gapsuch as 270, or 269, the potential of the corresponding conductor 227 or226 will be at a different voltage level from the particular conductor225 or 224 at which discharge is taking place, so that there is currentiiow, through the photoconductive layer, varying with the conductancethereof at the scanning point. This variable conductance effects avarying voltage drop across each of the resistors inserted in therespective leads 316 and 318 each of which may be employed to modulatetwo carrier frequencies respectively to transmit color imageinformation.

It will be understood, as before, that the conductors 227 and 226 whichact as color band filters will be the only means by which light mayreach the photoconductive layer, and will constitute a plane upon whichinformation in the form of pictures, diagrams, written material or thelike Will be projected as an image.

As before, the number of sets of conductive lines such as 227 and 226may be increased from two to three to utilize a three colorpicture-producing or camera scanning apparatus, as will be readilyunderstood. It will be further understood that the rate of dischargetravel from left to right along gaps 270 and gaps 269 will be at thesame rate of speed, and that both sets of gaps may be triggered bydischarges at gaps 274 and 273, substantially simultaneously, withdischarge at gap 273 following discharge at gap 274 by an interval oftime no longer than one half the time for the discharge to move from onegap 270 to the next.

While scanning has been described as being effected as unidirectional,that is in one direction horizontally and one direction vertically, itwill be understood that bidirectional scanning either horizontally orvertically or both could be employed using the inventive concepts hereinset forth. This may be accomplished by periodically reversing the field.If the period of reversal be within the travel time of the dischargethrough the row of gaps, the discharge may be maintained withouttriggering, and triggering could be effected anywhere along the line ofgaps, for starting purposes. Thus if the field varies sinusoidally thevelocity of discharge travel can be made to vary sinusoidally.

It will be apparent to those skilled in the art that the invention maybe employed by arranging the conductors in a polar coordinate fashion,utilizing a plurality of concentric circular conductors of graduallyincreasing radius, in combination with a plurality of radial conductorsangularly spaced in a uniform manner, the circular and radial conductorbeing spaced by a layer of electricallight transducer material, that isphotoconductive or electroluminescent material as set forth. The radialconductors would preferably have at their peripheral ends a gap, toproduce a circumferential series of gaps, so that the discharge maytravel from gap to gap circumferentially. A triggering gap may be usedto initiate circumferential discharge, and may be employed to controlthe period for each 360 of travel. Control may be effected by pulsingthe magnetic field which will be associated with the gaps to producecircumferential travel.

The circular conductors may each have a lead extending away from theplane of the conductors and each lead will have a gap, and the gaps willbe arranged in a row with uniform spacing and in a suitable magneticfield. As herein referred to, a triggering gap will be provided adjacentan end gap to initiate each travel of the discharge along the row ofgaps.

The term electrical-light transducer as used herein is intended toinclude electroluminescent material as well as photoconductive material.

Although a single embodiment of the invention has been illustrated anddescribed with variations, it is to be understood that the invention isnot limited thereto. As various changes in the construction andarrangement may be made without departing fro-m the spirit of theinvention, as will be apparent to those skilled in the art, referencewill be had to the appended claims for a definition of the limits of theinvention.

What is claimed is:

1. A scanning tube, comprising a plurality of parallel layers including,successively, a first layer containing a plurality of spaced firstconductors, a second layer of electroluminescent material, a third layercontaining a plurality of spaced second conductors, a fourth layer oftransparent insulating material, a fifth layer comprising a firsttransparent conductive film, a sixth layer comprising a photoelectricmaterial, an opaque seventh layer comprising insulating materialcontaining a multiplicity of minute conductive elements insulated onefrom another, an eighth layer comprising an electrical light transducermaterial, and a ninth layer comprising a second transparent conductivefilm, a substantial number of said first conductors overlapping in apredetermined angular relationship a substantial number of said secondconductors to provide a scanning area, each of said first and secondconductors containing a gap outside of said overlapping area, the gapsof said first and second conductors being disposed in rows extendingtransversely of said conductors, respectively, first and second commonterminal means connecting the ends of said first and second conductors,respectively, beyond the respective gaps, first and second triggeringconductor means connected with said first and second common terminals,respectively, each of said triggering conductor means containing atriggering gap disposed adjacent to a gap of said first and secondconductors, respectively, an impervious envelope enclosing all of thegaps and containing an ionizable media; means for applying a directcurrent potential across the first and second common terminals of avalue slightly less than that required to create discharge in the gapsof the conductors connected thereto except upon the ionization of themedia in the immediate region of and from an established discharge in anadjacent gap, means for periodically applying to said first and secondtriggering conductor means potentials for creating triggering dischargesat said triggering gaps, respectivey, and magnetic control meansextending along the lines of the respective gaps for causing a dischargeestablished in each triggering gap to move transversely and sequentiallyfrom gap to gap.

2. Apparatus as defined in claim 1, and further including means forapplying across said first and second conductive films a high frequencyinformation modulated signal potential.

3. Apparatus as defined in claim 1 wherein said eighth layer ofelectrical light transducer material comprises an electroluminescentmaterial.

4. Apparatus as dened in claim 1 wherein said eighth layer of electricallight transducer material comprises a photoconductive material.

5. Apparatus as defined in claim 4, and further including means forprojecting upon said eighth layer of photoconductive electrical lighttransducer material an image having varying light intensities.

6. Apparatus as in claim 1 wherein the sequential rate of energizationof conductors of one layer is a multiple of the sequential rate ofenergization ofthe conductors of the other of said layers. i

7. Apparatus as defined in claim l wherein said control means causes ahigher rate of movement of the discharge between the gaps of said secondconductors than the rate of discharge movement between the gaps of saidfirst conductors.

8. Apparatus as defined in claim 1 and further including third andfourth common terminal means, and a plurality of like resistorsconnecting the other ends of said first and second conductors with saidthird and fourth common terminal means, respectively, the resistancevalue of said resistors substantially matching the resistance of theassociated gap during the discharge thereof, whereby any conductorduring discharge at the gap associated therewith is substantially atmid-potential of the direct current voltage source to effectsubstantially zero potential scanning of the electrical transducermaterial.

9. Apparatus as defined in claim 8, wherein first and second groups ofsaid first conductors contain gaps arranged in transverse rows outsideand on opposite sides of said overlapping area, respectively, and firstand second groups of said second conductors also contain gaps arrangedin transverse rows outside and on opposite sides of said overlappingarea, respectively.

10. Apparatus as defined in claim 1 wherein said eighth layer of lighttransducer material and said ninth layer of conductive film are eachdivided into separate parallel strips, the strips in one of said layersregistering with strips in the other thereof, said strips of each layerbeing arranged in groups, each strip of a group in one of said layershaving a different color characteristic from the adjacent strip of itsgroup, all of the strips of every group being arranged with respect toeach other in an identical color relationship, means electricallyinterconnecting together only the corresponding strips of each group insaid ninth layer, means for separately applying between each of therespective sets of interconnected strips and said fifth layer ofconductive film a high frequency information signal modulated inaccordance with the color characteristic of each set of strips, each oneof said groups of strips being in registry with a conductor in one ofthe first or third conductor layers.

11. Apparatus as in claim 10y wherein each group comprises twoside-by-side strips only, each of the strips of a group having adifferent color characteristic, each of said groups being identical andforming a two-color display means.

12. Apparatus in claim 10' wherein the strips of the ninth layer ofconductive film have color characteristics and wherein the strips of theeighth light transducer layer are photoconductive whereby the apparatusfunctions as a camera. Y

13. Apparatus as defined in claim 1 wherein said ninth layer ofconductive film is of semi-transparent material and is divided into setsof alternate strips, each of said sets transmitting one band of colordifferent from another set, means electrically interconnecting togetherthe same strips of each set, means for separately applying between eachset of interconnected strips and said fifth layer of conductive film ahigh frequency information signal modulated in accordance with the colorcharacteristics of said strips, the adjacent strips of the respectivesets being in registry with a respective conductor in one of the firstconductor layers. 4

14. A scanning tube comprising a plurality of parallel layers including,successively, a first layer containing a plurality of spaced rstconductors, a second layer of electroluminescent material, and a thirdlayer containing a plurality of spaced second conductors, a substantialnumber of said rst conductors overlapping in angular relationship asubstantial number of said second conductors to provide a scanning area,each of said rst and second conductors contains a gap outside of saidoverlapping area, the gaps of said rst and second conductors beingdisposed in rows extending transversely of said conductors,respectively, rst and second common terminal means connecting the endsof said rst and second conductors, respectively, beyond the respectivegaps, 'rst and second triggering conductor means connected with saidfirst and second common terminals, respectively, each of said triggeringconductor means containing a triggering gap disposed adjacent to a gapof said first and second conductors, respectively, an imperviousenvelope enclosing all of the gapsvand containing an ionizable media;means for applying a direct current potential across the rst and secondcommon terminals of a value slightly less than that required to createdischarge in the gaps of the conductors connected thereto except uponthe ionization of the media in the immediate region of and from anestablished discharge in an adjacent gap, means for periodicallyapplying to said first and second triggering conductor means potentialsfor creating triggering discharges at said triggering gaps,respectively, and magnetic control 12 means extending along the lines ofgaps for causing a discharge established in each triggering gap to movetransversely and sequentially from gap to gap.

15. Apparatus in accordance with claim 14 wherein said magnetic meanscomprises pole pieces disposed along the opposite sides of said layersin alignment with the respective lines of gaps.

16. Apparatus in accordance with claim 15 including yokesinterconnecting the respective pairs of pole pieces.

References Cited UNITED STATES PATENTS 2,598,392 5/1952 Kaell et al313-156 2,612,625 9/1952 Hullegard 315-344 2,858,363 10/1958 Kazan178-5.4 2,944,155 7/1960 Mayer 1785.4 3,012,095 12/1961 Skellett 1785.43,042,834 7/1962 Nicoll 315-169 3,142,819 7/1964 Duinker et al. 178-5.43,152,222 10/1964 Loebner 178-54 3,264,479 8/1966 Peek 315-169 JOHN W.CALDWELL, Acting Primary Examiner. DAVID G. REDINBAUGH, Examiner.

I. A. OBRIEN, Assistant Examiner.

1. A SCANNING TUBE, COMPRISING A PLURALITY OF PARALLEL LAYER INCLUDING,SUCCESSIVELY, A FIRST LAYER CONTAINING A PLURALITY OF SPACED FIRSTCONDUCTORS, A SECOND LAYER OF ELECTROLUMINESCENT MATERIAL, A THIRD LAYERCONTAINING A PLURALITY OF SPACED SECOND CONDUCTORS, A FOURTH LAYER OFTRANSPARENT INSULATING MATERIAL, A FIFTH LAYER COMPRISING A FIRSTTRANSPARENT CONDUCTIVE FILM, A SIXTH LAYER COMPRISING A PHOTOELECTRICMATERIAL, AN OPAQUE SEVENTH LAYER COMPRISING INSULATING MATERIALCONTAINING A MULTIPLICITY OF MINUTE CONDUCTIVE ELEMENTS INSULATED ONEFROM ANOTHER, AN EIGHTH LAYER COMPRISING AN ELECTRICAL LIGHT TRANSDUCERMATERIAL, AND A NINTH LAYER COMPRISING A SECOND TRANSPARENT CONDUCTIVEFILM, A SUBSTANTIAL NUMBER OF SAID FIRST CONDUCTORS OVERLAPPING IN APREDETERMINED ANGULAR RELATIONSHIP A SUBSTANTIAL NUMBER OF SAID SECONDCONDUCTORS TO PROVIDE A SCANNING AREA, EACH OF SAID FIRST AND SECONDCONDUCTORS CONTAINING A GAP OUTSIDE OF SAID OVERLAPPING AREA, THE GAPSOF SAID FIRST AND SECOND CONDUCTORS BEING DISPOSED IN ROWS EXTENDINGTRANSVERSELY OF SAID CONDUCTORS, RESPECTIVELY, FIRST AND SECOND COMMONTERMINAL MEANS CONNECTING THE ENDS OF SAID FIRST AND SECOND CONDUCTORS,RESPECTIVELY, BEYOND THE RESPECTIVE GAPS, FIRST AND SECOND TRIGGERINGCONDUCTOR MEANS CONNECTED WITH SAID FIRST AND SECOND COMMON TERMINALS,RESPECTIVELY, EACH OF SAID TRIGGERING CONDUCTOR MEANS CONTAINING ATRIGGERING GAP DISPOSED ADJACENT TO A GAP OF SAID FIRST AND SECONDCONDUCTORS, RESPECTIVELY, AN IMPERVIOUS ENVELOPE ENCLOSING ALL OF THEGAPS AND CONTAINING AN IONIZABLE MEDIA; MEANS FOR APPLYING A DIRECTCURRENT POTENTIAL ACROSS THE FIRST AND SECOND COMMON TERMINALS OF AVALVE SLIGHTLY LESS THAN THAT REQUIRED TO CREATE DISCHARGE IN THE GAPSOF THE CONDUCTORS CONNECTED THERETO EXCEPT UPON THE IONIZATION OF THEMEDIA IN THE IMMEDIATE REGION OF AND FROM AN ESTABLISHED DISCHARGED INAN ADJACENT GAP, MEANS FOR PERIODICALLY APPLYING TO SAID FIRST ANDSECOND TRIGGERING CONDUCTOR MEANS POTENTIALS FOR CREATING TRIGGERINGDISCHARGES AT SAID TRIGGERING GAPS, RESPECTIVELY, AND MAGNETIC CONTROLMEANS EXTENDING ALONG THE LINES OF THE RESPECTIVE GAPS FOR CAUSING ADISCHARGE ESTABLISHED IN EACH TRIGGERING GAP TO MOVE TRANSVERSELY ANDSEQUENTIALLY FROM GAP TO GAP.
 10. APPARATUS AS DEFINED IN CLAIM 1WHEREIN SAID EIGHTH LAYER OF LIGHT TRANSDUCER MATERIAL AND SAID NINTHLAYER OF CONDUCTIVE FILM ARE EACH DIVIDED INTO SEPARATE PARALLEL STRIPS,THE STRIPS IN ONE OF SAID LAYERS REGISTERING WITH STRIPS IN THE OTHERTHEREOF, SAID STRIPS OF EACH LAYER BEING ARRANGED IN GROUPS, EACH STRIPOF A GROUP IN ONE OF SAID LAYERS HAVING A DIFFERENT COLOR CHARACTERISTICFROM THE ADJACENT STRIP OF ITS GROUP, ALL OF THE STRIPS OF EVERY GROUPBEING ARRANGED WITH RESPECT TO EACH OTHER IN AN IDENTICAL COLORRELATIONSHIP, MEANS ELECTRICALLY INTERCONNECTING TOGETHER ONLY THECORRESPONDING STRIPS OF EACH GROUP IN SAID NINTH LAYER, MEANS FORSEPARATELY APPLYING BETWEEN EACH OF THE RESPECTIVE SETS OFINTERCONNECTED STRIPS AND SAID FIFTH LAYER OF CONDUCTIVE FILM A HIGHFREQUENCY INFORMATION SIGNAL MODULATED IN ACCORDANCE WITH THE COLORCHARACTERISTIC OF EACH SET OF STRIPS, EACH ONE OF SAID GROUPS OF STRIPSBEING IN REGISTRY WITH A CONDUCTOR IN ONE OF THE FIRST OR THIRDCONDUCTOR LAYERS.